scholarly journals High-Redshift Radio Galaxies

1995 ◽  
Vol 10 ◽  
pp. 543-546
Author(s):  
George Miley
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Line Emission ◽  
Optical Emission ◽  
Delta Function ◽  
Radio Galaxies ◽  
Radio Continuum ◽  
Spatially Resolved ◽  
A Value ◽  
Optical Line

Radio galaxies are unique cosmological probes. As with radio-loud quasars, the presence of luminous radio continuum and optical line emission enable radio galaxies to be observed and recognized at large distances, up to z = 4.2. However, unlike the situation for most quasars, their optical emission can be spatially resolved from the ground and studied in detail.Progress in detecting distant radio galaxies has been rapid in recent years due to the use of CCDs and the exploitation of new selection criteria. Now, more than 60 radio galaxies are known with z > 2. More than half of these have been found by our group by concentrating on radio sources with the steepest spectra, most of these in a “Key Programme” of the European Southern Observatory. Although several people contributed to this Key Programme, most of the work was done by Huub Röttgering, who presented his Ph.D thesis in January and Rob van Ojik, who succeededhim. Redshifts of 1.5 to 4 correspond to a time when the Universe was 10% -20% of its present age. This was a crucial period in history when galaxy formation must have been rampant. It corresponds to the AGN era, a two-billion year “delta function” in the population evolution of luminous quasars and radio galaxies, when their space-density rose to a value several hundred times larger than the present density before the species mysteriously and suddenly became almost extinct.

Extended optical line emission associated with radio galaxies

1986 ◽  
Vol 64 (4) ◽  
pp. 392-397 ◽  
Author(s):  
Wil van Breugel
Keyword(s):  
Emission Line ◽  
Ambient Medium ◽  
Line Emission ◽  
Optical Emission ◽  
Radio Galaxies ◽  
General Properties ◽  
Extragalactic Jets ◽  
Optical Line

Observations of radio galaxies that have extended optical emission-line regions provide a new way of studying the interaction of extragalactic jets with their ambient medium. Their general properties are briefly reviewed and are illustrated using recent results on 4C 29.30 and Minkowski's Object.

scholarly journals Spatially resolved studies of extragalactic jets in high redshift radio galaxies

2014 ◽  
Vol 10 (S313) ◽  
pp. 231-235
Author(s):  
Leah K. Morabito ◽  
Adam Deller ◽  
J. B. R. Oonk ◽  
Huub Röttgering ◽  
George Miley
Keyword(s):  
High Redshift ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spatially Resolved ◽  
Long Baseline ◽  
Early Results ◽  
Spectrum Radio ◽  
Extragalactic Jets ◽  
Frequency Survey

AbstractThe correlation between radio spectral steepness and redshift has been successfully used to find high redshift (z ⩾ 2) radio galaxies, but the origin of this relation is unknown. The ultra-steep spectra of high-z radio sources make them ideally suited for studies with the Low Band Antenna of the new Low Frequency Array, which covers 10–80 MHz and has baselines up to about 1300 km. As part of an ongoing survey, we use the longest baselines to map the low-frequency (< 70 MHz) spatial distributions along the jets of 5 bright extended steep spectrum high-z radio sources. From this, we will determine whether the spectra change over these spatially resolved sources, thereby constraining particle acceleration processes. We present early results from our low-frequency survey of ultra-steep spectrum radio galaxies. The first low frequency long baseline images of these objects are presented.

scholarly journals Discovery of diffuse optical emission lines from the inner Galaxy: Evidence for LI(N)ER-like gas

2020 ◽  
Vol 6 (27) ◽  
pp. eaay9711 ◽  
Author(s):  
D. Krishnarao ◽  
R. A. Benjamin ◽  
L. M. Haffner
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Center ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Optical Emission ◽  
Hydrogen Gas ◽  
Emission Lines ◽  
Neutral Gas ◽  
Optical Line ◽  
Tilted Disk

Optical emission lines are used to categorize galaxies into three groups according to their dominant central radiation source: active galactic nuclei, star formation, or low-ionization (nuclear) emission regions [LI(N)ERs] that may trace ionizing radiation from older stellar populations. Using the Wisconsin H-Alpha Mapper, we detect optical line emission in low-extinction windows within eight degrees of Galactic Center. The emission is associated with the 1.5-kiloparsec-radius “Tilted Disk” of neutral gas. We modify a model of this disk and find that the hydrogen gas observed is at least 48% ionized. The ratio [NII] λ6584 angstroms/Hα λ6563 angstroms increases from 0.3 to 2.5 with Galactocentric radius; [OIII] λ5007 angstroms and Hβ λ4861 angstroms are also sometimes detected. The line ratios for most Tilted Disk sightlines are characteristic of LI(N)ER galaxies.

Erratum: "Radio Continuum Polarimetric Images of High Redshift Radio Galaxies" [A. J. 107,480(1994)]

1994 ◽  
Vol 107 ◽  
pp. 2299 ◽  
Author(s):  
C. L. Carilli ◽  
F. N. Owen ◽  
D. E. Harris
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Radio Continuum

Radio continuum polarimetric imaging of high redshift radio galaxies

1994 ◽  
Vol 107 ◽  
pp. 480 ◽  
Author(s):  
C. L. Carilli ◽  
F. N. Owen ◽  
D. E. Harris
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Radio Continuum ◽  
Polarimetric Imaging

A Detailed Study of High Redshift Radio Galaxies

1995 ◽  
Vol 149 ◽  
pp. 123-126
Author(s):  
H. Hippelein ◽  
K. Meisenheimer ◽  
M. Neeser
Keyword(s):  
High Redshift ◽  
Line Emission ◽  
Radio Galaxies ◽  
Fabry Perot

AbstractWe report on an ongoing survey of the extended line emission in high redshift radio galaxies, using a tunable Fabry-Perot etalon. Some results and suitable models are presented for individual sources.

scholarly journals Spatially resolving the relics: The inferring the physics driving the quenching of massive galaxies from kinematics at z ∼ 1 and beyond

2019 ◽  
Vol 15 (S352) ◽  
pp. 267-267
Author(s):  
Rachel Bezanson
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Spectroscopic Studies ◽  
Gas Reservoirs ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Galaxy Formation And Evolution ◽  
Ordered Motion

AbstractToday's massive elliptical galaxies are primarily red-and-dead, dispersion supported ellipticals. The physical process(es) driving the shutdown or ‘quenching’ of star formation in these galaxies remains one of the least understood aspects of galaxy formation and evolution. Although today's spiral and elliptical galaxies exhibit a clear bimodality in their structures, kinematics, and stellar populations, it may be that the quenching and structural transformation do no occur simultaneously. In this talk I will present evidence that early quiescent galaxies, observed much closer to their quenching epoch at z ∼ 1, retain significant rotational support (∼ twice as much as local ellipticals). This suggests that the mechanisms responsible for shutting down star formation do not also have to destroy ordered motion in massive galaxies; the increased dispersion support could occur subsequently via hierarchical growth and minor merging. I will discuss this evidence in conjunction with recent ALMA studies of the dramatic range in molecular gas reservoirs of recently quenched high redshift galaxies to constrain quenching models. Finally, I will discuss prospects for extending spatially resolved spectroscopic studies of galaxies immediately following quenching with JWST and eventually 30-m class telescopes.

scholarly journals Panchromatic study of the first galaxies with large ALMA programs

2019 ◽  
Vol 15 (S341) ◽  
pp. 12-16 ◽  
Author(s):  
A. Faisst ◽  
M. Béthermin ◽  
P. Capak ◽  
P. Cassata ◽  
O. Le Fèvre ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Optical Emission ◽  
Far Infrared ◽  
Photometric Redshifts ◽  
Galaxy Formation And Evolution ◽  
Major Player ◽  
Imaging And Spectroscopy ◽  
First Galaxies ◽  
Stellar Masses

AbstractThanks to deep optical to near-IR imaging and spectroscopy, significant progress is made in characterizing the rest-frame UV to optical properties of galaxies in the early universe (z > 4. Surveys with Hubble, Spitzer, and ground-based facilities (Keck, Subaru, and VLT) provide spectroscopic and photometric redshifts, measurements of the spatial structure, stellar masses, and optical emission lines for large samples of galaxies. Recently, the Atacama Large (Sub) Millimeter Array (ALMA) has become a major player in pushing studies of high redshift galaxies to far-infrared wavelengths, hence making panchromatic surveys over many orders of frequencies possible. While past studies focused mostly on bright sub-millimeter galaxies, the sensitivity of ALMA now enables surveys like ALPINE, which focuses on measuring the gas and dust properties of a large sample of normal main-sequence galaxies at z > 4. Combining observations across different wavelengths into a single, panchromatic picture of galaxy formation and evolution is currently and in the future an important focus of the astronomical community.

scholarly journals Radio Continuum Imaging of High‐Redshift Radio Galaxies

1997 ◽  
Vol 109 (1) ◽  
pp. 1-44 ◽  
Author(s):  
C. L. Carilli ◽  
H. J. A. Rottgering ◽  
R. van Ojik ◽  
G. K. Miley ◽  
W. J. M. van Breugel
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Radio Continuum

scholarly journals SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models

2020 ◽  
Vol 636 ◽  
pp. A42 ◽  
Author(s):  
M. Mingozzi ◽  
F. Belfiore ◽  
G. Cresci ◽  
K. Bundy ◽  
M. Bershady ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Theoretical Work ◽  
Universal Relation ◽  
Star Forming ◽  
Spatially Resolved ◽  
Integral Field Spectroscopy ◽  
Radial Profiles ◽  
Central Regions ◽  
Optical Line ◽  
Low Mass

We measured gas-phase metallicity, ionisation parameter, and dust extinction for a representative sample of 1795 local star-forming galaxies using integral field spectroscopy from the SDSS-IV MaNGA survey. We self-consistently derive these quantities by comparing observed line fluxes with photoionisation models using a Bayesian framework. We also present the first comprehensive study of the [S III]λλ9069,9532 nebular lines, which have long been predicted to be ideal tracers of the ionisation parameter. However, we find that current photoionisation model predictions substantially over-predict the intensity of the [S III] lines, while broadly reproducing other observed optical line ratios. We discuss how to nonetheless make use of the information provided by the [S III] lines by setting a prior on the ionisation parameter. Following this approach, we derive spatially resolved maps and radial profiles of metallicity and ionisation parameter. The metallicity radial profiles derived are comparable with previous works, with metallicity declining toward the outer parts and showing a flattening in the central regions. This is in agreement with infall models of galaxy formation, which predict that spiral discs build up through accretion of material, leading to an inside-out growth. On the other hand, ionisation parameter radial profiles are flat for low-mass galaxies, while their slope becomes positive as galaxy mass increases. However, the ionisation parameter maps we obtain are clumpy, especially for low-mass galaxies. The ionisation parameter is tightly correlated with the equivalent width of Hα [EW(Hα)], following a nearly universal relation, which we attribute to the change of the spectral shape of ionising sources due to ageing of H II regions. We derive a positive correlation between ionisation parameter and metallicity at fixed EW(Hα), in disagreement with previous theoretical work that predict an anti-correlation.

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